The second term here is pure gauge, since \(X_{2}\)  is a function of
\(x_{2}\)  only.The Kerr-Schild prescription for the double copy is sensitive to gauge choice on the
single copy side. The original single copy for Schwarzschild, for instance, was in an unusual gauge
[1]}. [2]} discusses this gauge issue in the Weyl double copy context, while [3]} relates monopoles in the double copy to singular gauge transformations. The first term matches the aligned
field gauge potential found in [4]} when \(e_{1} = 0,\ e_{2} = 2M\) . Thus, the single copy for \(D = 5\)  Myers-Perry proposed in
[1]} is an aligned field.
